A leak tester is used to detect the presence of a leak in a sealed article. Such a leak can render the article ineffective for its intended use.
In a known method, an article is sealed with a tracer gas, such as helium, in the article. The article is then placed in a chamber directly connected to a gas analysis instrument, such as a mass spectrometer. The mass spectrometer is capable of detecting the presence of the tracer gas. The mass spectrometer includes a vacuum pump which evacuates the chamber which encloses the article. If a leak is present in the article, the tracer gas will pass through the leak in the article into the mass spectrometer.
The known method requires a high vacuum for proper functioning of the mass spectrometer. During creation of the high vacuum, it is possible for most or all of a leaking tracer gas to be drawn from an article into the mass spectrometer and flow from the mass spectrometer. When the high vacuum is obtained, there may be an insufficient amount of leaked tracer gas flowing into the mass spectrometer to be detected. Thus, the mass spectrometer may indicate that the article is acceptable (no leaked tracer gas) when in fact the article is not acceptable.